Most of the member congregations of the UUA are in the United States and Canada, but the UUA has also admitted congregations from Australia, New Zealand, the Philippines and Pakistan (although UUA policy appears at present to be against admitting any new congregations from outside North America, rather having them form their own national bodies and having these bodies join the International Council of Unitarians and Universalists[original research?]). Until 2002, almost all member congregations of the Canadian Unitarian Council (CUC) were also members of the UUA and most services to CUC member congregations were provided by the UUA. However, after an agreement between the UUA and the CUC, since 2002 most services have been provided by the CUC to its own member congregations, with the UUA continuing to provide ministerial settlement services. Since 2002, some Canadian congregations have continued to be members of both the UUA and CUC while others are members of only the CUC.

The Church of the Larger Fellowship (CLF) is a member church of the Unitarian Universalist Association providing denominational services to persons unable to attend a physical congregation because of distance or mobility, or who wish to belong to a congregation other than their local congregation. Many of these are Unitarian Universalists in other countries, members of the military, prisoners or non-mobile elderly.

The UUA is headquartered at 24 Farnsworth Street, within Boston, Massachusetts which is the historical center of UnitarianChristianity in America. As of 2009, the UUA comprised 19 Districts, 1,041 congregations with 164,656 certified members and 61,795 church school enrollees served by 1,623 ministers.[10] However, as of 2011 the UUA had 162,796 certified members and 54,671 church school enrollees. This shows a decline of 1,860 members and 7,124 enrollees in church school since 2008. The UUA has, for the first time, also reported decline in average weekly attendance to 100,693 people. This is a drop of 1.5% on the 2010 reported figure.[11] Many atheists and humanists are also a part of the various congregations of the Unitarian Universalist Association.[12]

The UUA was given corporate status in May 1961 under special acts of legislature of the Commonwealth of Massachusetts and the State of New York. See Chapter 148 of the acts of 1960 of the Massachusetts legislature and Chapter 827 of the Acts of 1960 of the New York legislature. Copies of said Acts are attached to the minutes of the organizing meeting of the Association held in Boston, Massachusetts in May 1961 and also are printed in the 1961–62 Directory of the Association.

The UUA is not a denomination in the traditional sense; the UUA is an association of congregations with no one organization able to speak authoritatively for the whole. It is the congregations that have authority over the larger body, through the annual General Assembly of the Unitarian Universalist Association. Since the general public understands denomination much more readily than association of congregations, the distinction is generally omitted in conversation. Because of this relationship between the congregations and the association, Unitarian Universalist congregations have a congregational polity of governance. However, day-to-day decisions are made by the president, the moderator, and the Board of Trustees.

In its role as a national organization representing the congregations, the UUA is a member of various organizations, both religious and secular.

The UUA does not have a central creed in which members are required to believe, but they have found it useful to articulate their common values in what has become known as the Principles and Purposes. The first version of the principles was adopted in 1960, and the modern form was adopted in 1984 (including the 7th principle). They were amended once again in 1995 to include the 6th source. Both of these were added to explicitly include members with Neopagan, Native American, and other natural theist spiritualities.[13]

"We, the member congregations of the Unitarian Universalist Association, covenant to affirm and promote"

The inherent worth and dignity of every person;

Justice, equity and compassion in human relations;

Acceptance of one another and encouragement to spiritual growth in our congregations;

A free and responsible search for truth and meaning;

The right of conscience and the use of the democratic process within our congregations and in society at large;

The goal of world community with peace, liberty, and justice for all;

Respect for the interdependent web of all existence of which we are a part.

"The living tradition which we share draws from many sources:"

Direct experience of that transcending mystery and wonder, affirmed in all cultures, which moves us to a renewal of the spirit and an openness to the forces which create and uphold life;

Words and deeds of prophetic women and men which challenge us to confront powers and structures of evil with justice, compassion, and the transforming power of love;

Wisdom from the world's religions which inspires us in our ethical and spiritual life;

Jewish and Christian teachings which call us to respond to God's love by loving our neighbors as ourselves;

Humanist teachings which counsel us to heed the guidance of reason and the results of science, and warn us against idolatries of the mind and spirit.

Spiritual teachings of earth-centered traditions which celebrate the sacred circle of life and instruct us to live in harmony with the rhythms of nature.

"Grateful for the religious pluralism which enriches and ennobles our faith, we are inspired to deepen our understanding and expand our vision. As free congregations we enter into this covenant, promising to one another our mutual trust and support."

The Purposes of the Unitarian Universalist Association

The Unitarian Universalist Association shall devote its resources to and exercise its corporate powers for religious, educational and humanitarian purposes. The primary purpose of the Association is to serve the needs of its member congregations, organize new congregations, extend and strengthen Unitarian Universalist institutions and implement its principles.

The Association declares and affirms its special responsibility, and that of its member societies and organizations, to promote the full participation of persons in all of its and their activities and in the full range of human endeavor without regard to race, color, sex, disability, affectional or sexual orientation, age, or national origin and without requiring adherence to any particular interpretation of religion or to any particular religious belief or creed.

Nothing herein shall be deemed to infringe upon the individual freedom of belief which is inherent in the Universalist and Unitarian heritages or to conflict with any statement of purpose, covenant, or bond of union used by any society unless such is used as a creedal test.

General Assembly (GA) is held every year in June in a different city in the USA. Member congregations (and three associate member organizations) send delegates and conventioneers to participate in the plenary sessions, workshops, district gatherings, and worship services.

The UUA requests annual contributions from its member congregations. The requested contribution, known as Fair Share, is calculated for each congregation by multiplying an annually determined membership fee times the number of registered members of that congregation. The UUA also has alternative modes of raising funds. In order for congregations to participate in certain programming, they will pay a nominal fee. Some funds are earned through charitable gifts or estate planning. Additionally, the UUA pools together investment funds from congregations or other constituents and manages them for a small percentage.

UUA leaders concerned with membership numbers fluctuating from barely perceptible growth to slight decline, are working with a variety of experimental UU communities that represent alternative models of congregational formation—or that may point to new forms of affiliation.[14]

Two non-congregational organizations belong to the UUA as Associate Member organizations. Associate Member organizations are esteemed as inherently integral to the work of the UUA and its member congregations, and are accorded two voting delegates each to the annual General Assembly. The Associate Member organizations are the Unitarian Universalist Service Committee (UUSC), which is active in social change actions, and the Unitarian Universalist Women's Federation, which provides education and advocacy on women's issues. The Unitarian Universalist United Nations Office, which is a center of information and action at the United Nations, was an Associate Member organization until it became an office within the UUA in 2011.[15]

The UUA also recognizes many organizations as Independent Affiliate organizations. These organizations are created by Unitarian Universalists as needed to meet the special needs of the diversity within Unitarian Universalism. These groups may provide specialized spiritual support, work for specific social justice issues, provide support for religious professionals, etc.

The UUA owns Beacon Press, a nationally known publisher of both fiction and non-fiction books. Skinner House Books publishes books primarily of interest to Unitarian Universalists.

The UUA is governed by delegates elected to the annual General Assembly. GA delegates elect the president, the moderator, and members of the Board of Trustees.[16]

From when the association was established in 1961 until 2010, the president and moderator were each elected to four-year terms by delegates at General Assembly. An individual could not be elected to more than two successive terms. Candidates ran by petition. The 2010 General Assembly adopted a bylaw amendment, to take effect in stages beginning in 2013, making changes in the composition of the Board of Trustees and in the terms and election procedures for president and moderator.[17][18] Under the new system, the president and moderator are each limited to a single term of six years. A Presidential Search Committee[19] nominates candidates for president. The Board of Trustees nominates candidates for moderator. Individuals who are not nominated by the committee or the board may run by petition. The 2010 amendment also reduced the size of the Board of Trustees and changed the election process so that all trustees are elected by General Assembly. (The prior board consisted of one trustee elected by each UUA district and several at-large trustees elected by General Assembly.)

The president of the UUA is its CEO and the religious leader of Unitarian Universalism in the United States. The Rev. Peter Morales was elected at General Assembly in 2009 and re-elected in 2013. His successor will be elected in 2017 for a term of six years.

The moderator of the UUA is the chair of the Board of Trustees and is the presiding officer at General Assembly. The moderator is the highest UUA position traditionally held by laity. Moderator Jim Key was elected for a six-year term at General Assembly in 2013.[20]

The Religion in Life religious emblems program of UUA is no longer recognized by the Boy Scouts of America (BSA). The UUA published statements opposing the BSA's policies on homosexuals, atheists, and agnostics in 1992; and in 1993, the UUA updated Religion in Life to include criticism of these BSA policies.[21] In 1998, the BSA withdrew recognition of Religion in Life, stating that such information was incompatible with BSA programs. The UUA removed the material from their curriculum and the BSA renewed their recognition of the program. When the BSA found that the UUA was issuing supplemental material with the Religion in Life workbooks that included statements critical of discrimination on the basis of sexual orientation or personal religious viewpoint, the BSA again withdrew recognition.[22]

The Unitarian Universalist Scouters Organization (UUSO) created the Living Your Religion program in May 2005 as a parallel award for Unitarian Universalist youth.[23] The program was promoted at the 2005 National Scout Jamboree and shown as having BSA approval in the UUSO membership brochure and the Living Your Religion Guidebook.[24][25][26][27] The UUA has stated that the UUSO is not recognized as an affiliate organization.[28][29] As of March 2006, the UUSO has a stated goal to create a set of awards that are recognized by the UUA and BSA.[23]

In the wake of this controversy, a number of SpiralScouts International circles and dozens of Navigator USA Chapters have formed within congregations of the UUA, despite having no official affiliation with the UUA.[30]

Navigators USA,[30] was founded by volunteers of All Souls Unitarian Church in New York City after terminating its charter with Boy Scout Troop 103 because of the BSA policies. Its founders describe as "...committed to providing a quality scouting experience that is inclusive and available to all children and families regardless of gender, race, religion, economic status, sexual orientation and social background."[31] There are currently 120 chapters in the United States, plus a number in the UK, France, and Kenya.[32]

In addition to SpiralScouts and Navigators USA, the UUA website also suggests Camp Fire as an alternative scout-like organization that comports with UU principles.